Frontiers of supramolecular chemistry at solid surfaces

Mali, Kunal S.; Pearce, Nicholas; Feyter, Steven De; Champness, Neil R.

doi:10.1039/c7cs00113d

Cited by 210 publications

(238 citation statements)

References 93 publications

(124 reference statements)

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“…[1][2][3] In combination with the molecular resolution of surfaces provided by scanning tunneling microscopy (STM) this goal has been the driving force behind a wealth of research activity. [3][4][5][6] These studies use concepts from reticular synthesis 7 and molecular tectonics. 8 Rigid and planar molecular building blocks known as tectons are decorated with functional groups at specific positions.…”

Section: Introductionmentioning

confidence: 99%

Controlling the Two-Dimensional Self-Assembly of Functionalized Porphyrins via Adenine–Thymine Quartet Formation

Blunt

Toft

et al. 2018

J. Phys. Chem. C

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The development of supramolecular synthons capable of driving hierarchical two-dimensional self-assembly is an important step towards the growth of complex and functional molecular surfaces. In this work the formation of nucleobase quartets consisting of adenine and thymine groups was used to control the 2D self-assembly of porphyrins. Tetra-(phenylthymine) zinc porphyrin (Zn-tetra-TP) and tetra-(phenyladenine) porphyrin (tetra-AP) were synthesised and scanning tunneling microscopy (STM) experiments performed to visualize their self-assembly at the liquid-solid interface between an organic solvent and a graphite surface. Mono-component solutions of both Zn-tetra-TP and tetra-AP form stable 2D structures with either thyminethymine or adenine-adenine hydrogen bonding. Structural models based on STM data were validated using molecular mechanics (MM) simulations. In contrast, bi-component mixtures showed the formation of a structure with p4 symmetry consisting of alternating Zn-tetra-TP and tetra-AP molecules in a chessboard type pattern. The relative positions of the porphyrin components were identified from STM images via contrast changes associated with the zinc atom present in Zn-tetra-TP. MM simulations suggest that hydrogen bonding interactions within these structures are based on the formation of adenine-thymine (ATAT) quartets with Watson-Crick base pairing between adenine and thymine groups.

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Section: Introductionmentioning

confidence: 99%

Controlling the Two-Dimensional Self-Assembly of Functionalized Porphyrins via Adenine–Thymine Quartet Formation

Blunt

Toft

et al. 2018

J. Phys. Chem. C

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“…Some of these structures can be considered as soft self-assembled supramolecular analogues of the porous solid-state materials based on covalent organic frameworks (COFs) [36][37][38]. The observed tiling patterns are also similar to selfassembled 2D-nets formed on and stabilized by solid surfaces [39,40]. In the LC phases discussed here, these nets are expanded in the third dimension, with formation of honeycombs.…”

Section: Methodsmentioning

confidence: 72%

Effects of Lateral and Terminal Chains of X-Shaped Bolapolyphiles with Oligo(phenylene ethynylene) Cores on Self-Assembly Behaviour. Part 1: Transition between Amphiphilic and Polyphilic Self-Assembly in the Bulk

Poppe

Ebert

et al. 2017

Polymers

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Polyphilic self-assembly leads to compartmentalization of space and development of complex structures in soft matter on different length scales, reaching from the morphologies of block copolymers to the liquid crystalline (LC) phases of small molecules. Whereas block copolymers are known to form membranes and interact with phospholipid bilayers, liquid crystals have been less investigated in this respect. Here, series of bolapolyphilic X-shaped molecules were synthesized and investigated with respect to the effect of molecular structural parameters on the formation of LC phases (part 1), and on domain formation in phospholipid bilayer membranes (part 2). The investigated bolapolyphiles are based on a rod-like π-conjugated oligo(phenylene ethynylene) (OPE) core with two glycerol groups being either directly attached or separated by additional ethylene oxide (EO) units to both ends. The X-shape is provided by two lateral alkyl chains attached at opposite sides of the OPE core, being either linear, branched, or semiperfluorinated. In this report, the focus is on the transition from polyphilic (triphilic or tetraphilic) to binary amphiphilic self-assembly. Polyphilic self-assembly, i.e., segregation of all three or four incorporated units into separate nano-compartments, leads to the formation of hexagonal columnar LC phases, representing triangular honeycombs. A continuous transition from the well-defined triangular honeycomb structures to simple hexagonal columnar phases, dominated by the arrangement of polar columns on a hexagonal lattice in a mixed continuum formed by the lipophilic chains and the OPE rods, i.e., to amphiphilic self-assembly, was observed by reducing the length and volume of the lateral alkyl chains. A similar transition was found upon increasing the length of the EO units involved in the polar groups. If the lateral alkyl chains are enlarged or replaced by semiperfluorinated chains, then the segregation of lateral chains and rod-like cores is retained, even for enlarged polar groups, i.e., the transition from polyphilic to amphiphilic self-assembly is suppressed.

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“…The hBN surface was modelled by a flake consisting of 75 boron atoms and 75 nitrogen atoms with the edges capped by hydrogens. Atomic positions in the hBN flake were optimized at the ωB97X-D3-gCP/def2-SVP level of theory [1][2][3][4][5][6] and kept fixed in the subsequent calculations. The second hBN layer was placed parallel to the bottom hBN layer on top of the most energetically preferred adsorption site of PTCDI/hBN system determined for the S0, T1, and S1 electronic states.…”

Section: Non-resonant Shifts and Triplet Energy: Density Functional Tmentioning

confidence: 99%

Triplet Excitation and Electroluminescence from a Supramolecular Monolayer Embedded in a Boron Nitride Tunnel Barrier

et al. 2019

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We show that ordered monolayers of organic molecules stabilized by hydrogen bonding on the surface of exfoliated few-layer hexagonal boron nitride (hBN) flakes may be incorporated into van der Waals heterostructures with integral few-layer graphene contacts forming a molecular/2D hybrid tunneling diode. Electrons can tunnel from through the hBN/molecular barrier under an applied voltage VSD and we observe molecular electroluminescence from an excited singlet state with an emitted photon energy h > eVSD, indicating up-conversion by energies up to ~ 1 eV. We show that tunnelling electrons excite embedded molecules into singlet states in a two-step process via an intermediate triplet state through inelastic scattering and also observe direct emission from the triplet state. These heterostructures provide a solidstate device in which spin-triplet states, which cannot be generated by optical transitions, can be controllably excited and provide a new route to investigate the physics, chemistry and

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Frontiers of supramolecular chemistry at solid surfaces

Cited by 210 publications

References 93 publications

Controlling the Two-Dimensional Self-Assembly of Functionalized Porphyrins via Adenine–Thymine Quartet Formation

Controlling the Two-Dimensional Self-Assembly of Functionalized Porphyrins via Adenine–Thymine Quartet Formation

Effects of Lateral and Terminal Chains of X-Shaped Bolapolyphiles with Oligo(phenylene ethynylene) Cores on Self-Assembly Behaviour. Part 1: Transition between Amphiphilic and Polyphilic Self-Assembly in the Bulk

Triplet Excitation and Electroluminescence from a Supramolecular Monolayer Embedded in a Boron Nitride Tunnel Barrier

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